Nonlocking brake valve



Patented Apr. l,

NONLOCKING BRAKE VALVE Walter F. Benning, Toledo, Ohio, assigner to Mack Manufacturing Corporation, New York, N. Y., a corporation of Delaware 4 Application March 30, 1945, Serial No. 585,839

1- l 'I'his invention relates to vehicle brakes and moreparticularly to means for preventing locking 12 claims.A icl. 18s-181i of the brakes when. the brakes are applied to the brakes, any one of the brakes may lock first due to any one of various conditions, such as road surface under thewheel. the condition of the shoes and brake drum, or unequalized braking eiects produced by the brake applying means," producing an unbalanced retardng action on the vehicle tending to change the direction of movement of the vehicle. This is especially serious when one of the front or steering wheels locks.

I am -aware oi' attempts of others to prevent locking of the wheels to overcome the objections referred to by mechanisms and devices which have been satisfactory to a degree. Many oi those devices involve complicated mechanisms and some of them are dependent on the use of governors.

It is therefore an object of this invention to provide improved means more particularly applicable to fluid operated brakes for use on automobile wheels, for automatically partially releasing the brakes of a wheel Just before the wheel would cease to rotate as it is decelerated by the application of the brakes, the" :by preventing locking of the wheel and producing maximum braking effects to bring the vehicle to a stop.

It is a further object of this invention to provide means to release the pressure in a brake operating pressure cylinder as the decelerated speed of the wheel approaches zero, by a simple bleeding valve controlled by a pilot frictionally engaging the brake drum and so supported and controlled as to move with the brake drum when the brakes are applied, and to move counter to the movement of the brake drum Just before the brake drum would stop under locking braking action in service.

Other objects of this invention will appear from the following description taken in connection with the drawings in which Figure i is a side view of a braking -mechanism in which my invention has been incorporated, and

2 Figure 2 is a view in vertical section' on the line 2-2 of Figure 1. l In the drawings, the brake drum indicated at 4 may be of any standard construction and may -be supported on the vehicle wheel in any suitable manner.

Cooperating with the interior surface of the flange of the brake drum is a pair of brake shoes 5 and 6, also of any suitable and preferred con-4 struction, shown as pivoted at 1 and l on lugs carried by a brake shoe supporting member I0, supported in any well-known manner on the wheel axle housing. Also supported on a lug on the member II! is a iuld actuated brake shoe operating means I2 which is shown diagrammatically as it may be of any suitable well-known construction, for applying expanding and separating pressure against the free ends oi the brake shoes. Fluid under pressure is supplied to the means I2 through avpipe I4. Preferably there is a pipe L4' for each brake to which :fluid under pressure is supplied through a plural ported valve from a main supply pipe not shown. y In order not to interfere with the customary operation and control oi the brake, except to prevent locking of the wheels, I have provided a i bleed valve to exhaust fluid from the pipe I4 and fluid brake operating means :lust lbefore the wheel would ordinarily be stopped by the braking action produced under the control of the drive if such valve were not provided.

The valve comprises a casing I8 which is supported on the member I0 by any suitable means.

A The body of the casing may be a cylinder I1 and one of its ends I 8 may be removable to provide access to the valve chamber, and its other end I9 may be welded or otherwise secured thereto and may be secured by any suitable means to the member I0.

The cylinder I1 is provided with oppositely f,

located radial ports 20 and ZI, the port 2li communicating with a pipe 23 connected to the fluid pressure pipe Il and the port 2| communicating with the atmosphere.

Cooperating with the ports 20 and 2| is a sliding valve block 25 which is provided with a through-port 26 that may be brought into registration with the ports 20 and 2l to connect the i When the valve block 25 is moved to the right or left, it seals the end of the pipe 23 permitting control of the brake in the usual manner. 'Ihe rate of bleeding may be controlled by the size Y.

the exterior of the casing by means of which it may be operated.

For the purpose of controlling and operating the valve, I employ a pilot 30 provided with an outer end or head 3| of any suitable shape for frlctional engagement with the inner face of the flange of the brake drum 4, and I prefer to have it 'engage the flange of the drum Within the area engaged by one of the brake shoes shown here as the brake shoe 6. For this purpose, the brake shoe 5 and its friction facing 32 are provided with openings or notches 33 an'd34 in their edges of slightly longer dimensions in the 'direction of the length of the brake shoe than that of the outer end or head 3| of the pilot 30 so that the head 3| of the pilot may travel short distances to the right or left with respect to the brake shoe depending upon the direction of movement of the wheel and brake drum.

The pilot 30 is slotted and pivoted intermediate of its ends on a pivot pin 3B supported on the member I0 and at its inner end it is provided with a pin 31 extending into a vertically elongated slot 38 in the head 39 of the valve stem 2T so that the pilot may move radially and may pivot without applying a force laterally of the valve stem.

A spring 4| connects the inner end of the pilot to the free end of an arm 43 supported on a pivot pin 44 mounted in a lug on the member I0 and connected intermediate of itsv ends by a link 46 to a lugl on the brake shoe 6. As the brake shoe is moved outwardly into braking engagement with the flange of the drum, the head 3| of the pilot is resiliently pressed into working frictional contact with the inner face of the flange on the drum.

For the purpose of supporting the pilot normally out of contact with the ange of the brake drum and for centering the pilot and for returningit into its normal lor home position shown, I

v provide springs 50 and 5| located on opposite sides of the pilot and connected thereto and to lugs 52 and 53 on the brake shoe 6 through the intermediary of tensioning and adjusting screws 54 and 5,5. By this means the springs 50 and 5| may be tensioned to support the head of the pilot at the proper distance from the ange of the brake drum and to center the pilot and valve block 25 and to overcome thev drag of friction on the head of the pilot by the flange of the drum the friction of the drum on the head of the pilot rocks the pilot to close the bleeding valve placing the operation of the brakes again under the sole control of the operator. The lateral movement of the head of the pilot may be so short and the parts may be so proportioned and adjusted that thepressure onthe brake shoes will be alternately decreased and increased in rapid succes- 4 sion which is known to be desirable when run. ning on slippery roads.

While I have described my invention in detail with reference to a preferred emodiment thereof, it is to be understood that this is not to be considered limiting, and that I reserve the right to all such modications and changes as fall within the principles of this invention, and the scope oi' the appended claims.

Iclaim:

1. The combination with a rotatable member, a brake, and means for applying said brake with pressure tending to lock said member against rotation,v of a brake controlling element mounted for movement into engagement with said member and also for movement by and with said member, means for moving said element into engagement with said ,member as an incident to applying the brake, means for restoring said element against the action of said memberas the speed of said member is reduced by said brake to a point just short of zero speed and means controlled by said element in its restored position to reduce the braking` effect produced by said brake so as to prevent said brake from locking said member against rotation. y

2. The combination with a rotatable member rotatable in either direction, abrake, and means for moving said brake against said member with pressure tending to lock said member against rotation, of a brake controlling element, means for movably supporting said element for movement against said member and for movement thereby in either direction upon the `rotation of said member, means for moving said element against said memberas an incident to the movev ment of said brake against said member, means for restoring said element against the action of said member to a central position as the speed of rotation of said member is reduced by said brake to a point just-short of zero speed, and means controlled by said element invits restored central position to reduce the'braking eiect product by said brake so as to prevent said brakefrom locking said member against rotation. g

3. The combination with a rotatable member.

a brake, and means for pressingpxsaid brake against said member withl pressure tending to lock said member against rotatiomof a brake controlling` element normally spaced from said member and movably mounted for movement into the engagement with said member and for movement with said member; means for moving said element into engagement with said member as an incident to pressing said brake into engagement with said member so as to be moved by said member upon rotation thereof; means for restoring said element from the position into which it is moved by said member against the action of said member as the speed of said member is reduced by said brake to a point just short of zero speed and means controlled by said element in said restored position for reducing the braking eiiect produced by said brake so as to Prevent said brakefrom locking said member against rotation.

4. The combination with a rotatable member, a brake and fluid pressure actuated means for operating said brake, of a brakecontrolling element, means for movably supporting said element for movementinto engagement with said member and for movement by and with said member, means for restoring said element from a. position into which it has been moved by said member against the action of said member as the speed of said member is decelerated to a point just short of zero speed, and means controlled by said element in said restored position to reduce the pressure of the fluid acting on said brake. e

5. The combination with a rotatable member, a brake and uid pressure actuating means for operating said brake, of a brake controlling element, means movably supporting said element for movement into the engagement with said member and for movement by said member, means for restoring said element from the position into which it is moved by said member against the action of said member as the speed ofsaid member is decelerated to a point just short of zero speed, and a bleeding valve for bleeding iiuid from said uid pressure actuating means moved into open position by said element as it is moved into said restored position.

6. The combination with a rotatable member, a brake, and means for pressing said brake against said member, of a brake controlling element, means movably supporting said element for movement into engagement with said member and for movement by and with said member, means for moving said element against said member including spring means, spring means for restoring said element from the position into which it is moved by said member against the action of said member as the speed of rotation is reduced to a point just short of zero speed, and means controlled by said element in such restored position for reducing the braking eiect o! said brake.

'7. The combination with a rotatable member, a brake. and means for moving said brake against said member. a. brake controlling element for reducing the braking effect of said brake, means for supporting said element for movement into engagement with said member and for movement by and with said member. means for moving said element into engagement with said member as said brake is applied, comprising yielding means connecting said element and said brake member, whereby, said element is moved by and with said member as it is rotated when the brake is applied. yielding means for restoring said eiement against tbe action of said member upon deceleration of the speed of said member to a Speed lust short of zero sneed for reducing the braking effect oi said brake and means oontrolled bv said element in such restored position to reduce the braking effect of the brake.

8. The combination with a. rotatable member, a brake, and means for pressing said brake against said member with pressure tending to lock said member against rotation of a brake controlling element. means for supporting said element `ior movement into Contact with said member and for movement by and with said member, means on said brake limiting such latter movement of said element. means for restoring said element from the position into which it is moved by said member against the action of said member as tbe speed of said member is reduced by said brake toa point iust short of zero speed, and means controlled by said element when so restored for reducing the pressure of said brake by such an amount as to prevent said brake from inciting said member against rotation.

The combination with a rotatable member, a brake, and means for pressing said brake against said member with pressure tending tov lock said memberagainst rotation, said brake being prov` p vided with a radially extending slot, of a movablyV mounted brake controlling element` projecting into said slotl and adapted to engage said mem-.

ber to be moved thereby into engagement with an end Wall of said slot, means for restoring said element against the action-of said member as the speed of said member is reduced by said brake to a point just short of zero, and means controlledV extending therethrough in a direction normal to the braking surface of said member, of a brake controlling element, means for supporting said element for movement into engagement with said member and for movement by said member in either direction upon rotation of said member into engagement with an end wall of said slot, means for restoring said element against the action of said member as the speed of rotation of said member decreases to a point just short of Zero, and means controlled by said element when so restored for reducing said pressure so as to prevent said brake from locking said. member against rotation.

11. The combination with a rotatable member, a brake and means for pressing said brake against said rotatable member with pressure tending to lock said member against rotation, of a brake controlling element, means supporting said element for movement into engagement with said member and for movement by said member upon rotation of said member, means for limiting the movement of said element by said member, means for restoring said element from the position to which it is moved by said member against the action of said member as the speed of said member is reduced by said brake to a point just short of Zero speed, and means controlled by said element when so restored for reducing the braking effect of said brake to an extent to prevent said brake from locking said member against rotation.

12. The combination with a rotatable member, a brake, and pressure means for applying the brake, of a brake control element, means for moving the control element into engagement with the rotatable member as an incident of applying the brake, means for restoring the control element against the action of the rotatable member as the rotational speed `thereof is braked down, and means controlled by the control element in its restored position to reduce the braking pressure of the brake.

WALTER F. BENNING.

REFERENCES cI-rnn 'UNITED STATES PATENTS Name Date Stoddard Deo. 26, i939 Certificate of Correction Patent No. 2,418,288. April 1, 1947. WALTER F. BENNING It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Column 4, line 43, claim 2, for

product read produced; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 20th day of May, A. D. 1947.

[iwi] LESLIE FRAZER,

First Assistant @ammissioner of Patents. 

